1. Field of the Invention
The present invention generally relates to an abutment structure, and more particularly to an abutment structure of a semiconductor cell.
2. Description of the Prior Art
Conventional standard cell libraries in semiconductor integrated circuits (IC) primarily contain a logic cell layout based in a metal oxide semiconductor (MOS) environment, in particularly a complementary metal oxide semiconductor (CMOS) environment. A standard cell is a pre-designed layout of transistors or non-specific collection of logic gates that are typically interconnected or wired together in a particular manner to perform a specific type of logical operation in an application specific IC (ASIC). A conventional ASIC layout is typically defined by an array of logic cells arranged in adjacent rows. Such a row 10 is shown in FIG. 1 published from U.S. Pat. No. 7,266,787.
FIG. 1 shows a physical layout design of a row of cell structures within a CMOS environment. The adjacent logic cells 12, 31, 32, 33, are bound by a power rail 14 and a ground rail 16. Each logic cell defines a specific logic circuit. The active areas or components of the logic cell include negative-channel diffusion 24, positive-channel diffusion 26, and gate 34 layers. The components of the logic cells are wired internally with vias 28 and metal layer 18, 20, 22 to form simple logic (NMOS and PMOS) gates to perform Boolean and logic functions, for example INVERTER (or NOT), AND, OR, NAND, NOR, XOR, XNOR, ADDERS, FLIP-FLOP, and the like. In the design of the interconnection layout, IC design rules must be observed, for example, minimum width of transistor width, minimum width of metal tracks, and the like.
A very important function of the standard cell libraries is for satisfying various logic cell layouts. A single abutment may be able to pass a design rule check (DRC). However, abutments of different cells may be not likely to pass the DRC simultaneously. Thus, it is important to let various cell layouts pass the DRC by using cells in the standard cell libraries to rapidly generate different abutment combinations.